The present invention relates to the measurement of the fuel consumption of the engine of a vehicle, whether the latter is moving or stationary. More precisely, it relates to an apparatus for measuring the fuel consumption of a vehicle engine which comprises a feed circuit comprising a pump and placed between a fuel tank and the engine, and an excess fuel return circuit placed between the engine and the tank.
Apparatuses for measuring the fuel consumption of an engine are already known, since this measurement is of undoubted interest to design departments working on combustion engines. It is highly desirable, however, that this consumption should be capable of being followed continuously because it represents the operating conditions of a vehicle. For example, in a heavy truck fleet, the consumptions need to be known for an optimum management of the transportation. However, even in the case of an individual automobile vehicle, knowledge of this consumption is highly desirable.
U.S. Pat. No. 4,134,301 describes an apparatus for measuring the fuel consumption of a combustion engine, comprising two flowmeters having float chambers. Temperature sensors measure the temperature of the fuel at the entry and at the exit and permit compensation of the flow values given by the flowmeters. The apparatus comprises gravity measuring devices and devices intended to purge the vapor bubbles which are formed. Such a laboratory apparatus cannot be employed in a vehicle because of the nature of the flowmeters (float chambers) and the high probability of bubble formation in the event of jerks and vibrations. Moreover, this laboratory apparatus does not yield very reproducible results at low flow rates since these are disturbed by the presence of vapor bubbles, even in a very small quantity. The cost of this apparatus is moreover very high.